I cannot seem to find this problem addressed before. I have used Thunderbird for years as my primary email account but now am finding that some emails in the Gmail account do not ever download to Thunderbird. I have looked for this problem but have not found an answer that works. The emails in question clearly show up on my phone (Android using the native Gmail app) but I cannot get to them on the Thunderbird platform. It is only a few emails that do this but, of course, they have been the most critical. I have to use two email programs but so far that is the only solution I have found.